I just read this on a local forum and was shocked. I took the K&N to be the de facto 'good' replacement for the paper filter.

LOOK at that dirt! (HKS)



http://forums1.roadfly.com/porsche/f...4959457&page=1
http://www.max-boost.co.uk/max-boost...ilter_test.htm
http://www.bolhuijo.com/airflowtest/

 

You sound naive. I don't think anyone would argue that aftermarket filters filter as well as OEM.

Anyway, the vast majority of people here lose their engines in one of two ways, detonation and bad coolant seals, not dirt.

 

Most modded FD's I've seen here have aftermarket intakes. Most of them aren't cold air (just sucking in hot engine air).

Combine that fact + sucking in dirty air has to contribute to less than optimal engine performance/reliability.

My stock FD runs perfect, no mods. I put in a K&N (drop in) but I'll be pulling it out for OEM paper filter because I'd rather not take the chance.

 

I don't know.. There are many single turbo guys that uses fine metal mesh as filter or No filter. I've not heard any of them blowing their motor because of filteration issue.

Also as the second website points out, small amounts of dirt/carbon might affect the Air Flow Meters. But, 3rd gens don't have that.

I guess if you really want to have clean air, put a hepa filter.. j/k.. Please, No on try that!

 

I would not doubt that many aftermarket filters such as K&N do not filter all that well. If I could still use my stock airbox I'd certainly use an OEM filter. But due to space constraints I must use a K&N. As was stated above my engine will probably die due to other reasons first.

In regards to people who just run little mesh screen over their turbos... that's a really bad idea for any type of regularly driven vehicle. Sure it's fine if it's a show car and hardly driven or maybe just used for a bit of drag racing. But I challenge anyone to make a rotary last under daily driving conditions with just screen instead of a filter.

 

I've seen an intercooler about 70% clogged with a dirt/oil mix. Took a few hours to clean it all out with gasolone.

 

Two data points on long-term use of K&N filters:

1. My 1974 Chevy G30 van used to tow my Formula-Continental racecar has had a K&N drop-in replacement filter for about the last 150,000 miles. It has an additional cold-air inlet to the filter housing. The engine has not suffered any ill effects, and I do not see significant dirt inside the filter or in the carb.

2. My FD has had a K&N filter system (PFS air intake with dual-outlet tapered-oval filter enclosed in a housing) for ~45,000 miles. Again, no noticeable ill effects, and no significant amount of dirt in the intake tract. I'm at ~52K with the original engine.

IMO, three things (at least) could make a K&N-type filter less efficient than it could be:

1. Direct exposure to turbulent, fast-moving engine-compartment air - these filters need low air velocity through the element for the filter oil to attract and trap dirt. Very high velocity air will carry the dirt with it, possibly right through the filter.

2. Lack of sufficient (or correct type) oil on the cloth.

3. Abuse of the filter element, resulting in gaps that allow dirt through.

None of this is to suggest that a K&N filter cleans the air as well as the better stock paper filters, but for the performance increase, I think it's quite acceptable if used carefully.

 

Huh?

You bought a K&N filter but want to pull it out because the HKS piece-o-crap foam filter is abysmal? I don't see your logic. The K&N didn't do bad at all in this test (however valid it may be).

Unless you're sucking in rocks (or use a tshirt as an air filter) I doubt you'll ever hear of anyone "blowing" their engine with a shitty air filter. It's the premature failure & excessive wear that no one ever talks about, mostly because we have no tool to measure it except for longevity & teardown analysis. That, and too many of these engines die well before their time anyway due to poor owner management.

Boy, do I need a cup of coffee.

 

I ran a PFS intake for over 2 years....the inside of the intake box would be completely filthy...dirt, leaves, even a business card!, but the intake piping post K&N filters was always spotless.

People have been running K&Ns for almost 40 years....if they really were that bad at filtering they would not be so successful. I agree completely with DaveW about possible causes of poor filtration.